Camouflet device



June 30, 1970 C. H. BROWN CAMOUFLET DEVICE Z Sheets-Sheet 1 Filed Sept.27. 1968 INVENTOR CLAUDE H. BROWN BY b a/M, Swamp wedca 7 Hat/u:

ATTORNE f3 June 30, 1970 c. H.-BROWN CAMOUFLET DEVICE 2 Sheets-Sheet 2Filed Sept. 2'7. 1968 United States Patent O 3,517,469 CAMOUFLET DEVICEClaude H. Brown, Arlington, Tex., assignor to Jet Research Center, Inc.,Arlington, Tex., a corporation of Texas Filed Sept. 27, 1968, Ser. No.763,059 Int. Cl. E02d 5/80 US. Cl. 52-155 4 Claims ABSTRACT OF THEDISCLOSURE A camouflet device which is adaptedto haveapplied thereto aninitial accelerating force for propelling the device downwardly into theground. The camouflet device in cludes a body, containing an inertialmember mounted for free movement between vertically spaced upper andlower positions. A detonator is carried by the inertial member.Detonating means is mounted within the body for movement between safetyand firing positions of the detonating means. In the firing position thedetonating means is positioned to be struck by the detonator when theinertial member moves to the lower position, to thereby detonate thedetonator. In the safety position, the detonating means is spaced out ofcontact with the detonator. Passage means in the body admits earth intothe body upon contact with the ground to force the detonating means fromthe safety to the firing position.

BACKGROUND OF THE INVENTION This invention relates to a camouflet devicefor an explosive earth anchor. The camouflet is intended to explosivelyexpand the lower end of the anchor after it has been propelled into theground. In particular, the invention relates to a camouflet devicesuitable for use with a pipe line stake.

In securing an object to an immersed earth surface, such as the sea bed,it is sometimes advantageous to utilize an explosively actuated earthanchor. One recent use for an earth anchor has been for the purpose ofsecuring oil or gas pipe lines to the sea bed.

Typically, an earth anchor may include a slender elongate stakepropelled downwardly out of a housing by explosion of a first explosivecharge. A second or camouflet charge in the head of the stake isdetonated once the stake has been driven into the ground to expand thehead of the stake below ground level to secure it in the earth.

With such an arrangement, it is particularly important to insure thatthe camouflet charge does not fire prematurely while the stake is stillmoving into the ground, before the lower end of the stake has reachedits desired below ground location. It is also important that thecamouflet charge should be in a safe condition while the stake is beinghandled by personnel prior to installation.

For this reason, some prior earth anchors have included various forms ofdelay train to the camouflet charge to fire a predetermined timeinterval after initiation of the first or propelling charge. However,with a system of this type, operating on the basis of a predeterminedtime delay, there may be problems in correlating the time delay inseconds with the desired penetration of the lower end in feet. This mayarise because the necessary time-distance relationship is hard toascertain, particularly when operating in submerged strata varying fromsoft mud to rock. It would therefore be desirable to provide an armingsystem for the camouflet charge which functioned in response to themotion characteristics of the stake through the strata so that thecamouflet charge did not explode prematurely.

One prior arming system for this purpose includes an 3,517,469 PatentedJune 30, 1970 "Ice inertial member carrying a detonator for thecamouflet charge. During initial downward acceleration of the stake intothe ground, inertia forces hold the inertial member in an upper positionwithin the stake. However, as the device decelerates to rest, theinertial member carries the detonator down to a lower position undergravity to impinge onto a detonating pin to cause detonation. Initially,the detonating pin is located in a safety position within the stake,spaced out of contact with the lower position occupied by the detonatorso that accidental firing of the unit cannot occur. However, on entry ofthe device into the ground the detonating pin is advanced into a firingposition in which it may be struck by the detonator when it moves to itslower position. Movement of the detonating pin to the firing position iseffected by an arming mechanism including an earth-engaging propellerwhich is rotated upon downward movement through the earth to permit thedetonating pin to be moved to the firing position.

Although this prior device may be satisfactory for some purposes, theconstruction of the earth-engaging propeller and associated rotarystructure renders the tool complex and costly. In addition, aparticularly serious problem may arise if the ground to be penetrated isparticularly hard as the relatively vulnerable, propeller-like armingdevice may be ripped off during passage of the tool into the groundbefore the detonating pin has been moved to its firing position. In thisevent, the camouflet charge may never be detonated with the result thatthe stake may be inadequately secured to the ground.

OBJECTS AND SUMMARY OF INVENTION It is therefore a general object of theinvention to provide a camouflet device which obviates or minimizesproblems of the type previously noted.

It is a particular object of the invention to provide a camouflet devicecapable of unimpaired operation even under circumstances when the deviceis to he propelled into ground of unusually hard characteristics.

It is another object of the invention to provide a camoufiet device ofthe type generally described, which is of a particularly simple and lowcost construction.

A camouflet device according to a preferred embodiment of the inventionis intended to accomplish at least some of the foregoing objects. Thecamouflet device is adapted to have applied thereto an initialaccelerating force for propelling the device downwardly into the earth.The device includes a longitudinally extending body which is adapted tobe disposed vertically during downward movement. An inertial member ismounted for free longitudinal motion within the body and occupies alower position when under the influence of gravity alone. Dur ingdownward acceleration of the body into the ground, the inertial memberlags behind the body to occupy an upper position within the body spacedabove the lower position. A detonator is connected with and carried bythe inertial member. Detonating means is provided for detonating thedetonator upon impact therewith. The detonating means is mounted in thebody for movement between safety and firing positions. The detonatingmeans, in the firing position, is positioned to be struck by thedetonator when the inertial member moves to the lower position thereof.The detonating means, in the safety position thereof, is spaced out ofcontact with the detonator in all positions thereof. Passage means inthe body is adapted to direct earth inwardly of the body on impact ofthe body with the ground. The earth entering the passage means contactsthe detonating means to move it to the firing position.

By this construction, it will be appreciated that detonation of thedetonator is prevented while the device is still accelerating downwardlythrough the earth strata,

thereby avoiding premature detonation of the camouflet device.

In addition, safety of personnel is enhanced by initially positioningthe detonating means so that it is spaced out of any possible contactwith the detonator prior to entry of the device into the ground.

Also significant is the manner in which the ground surface is utilizeddirectly to effect arming of the detonating means, by causing the earthentering the passage means to function as a piston to move thedetonating means to the firing position.

THE DRAWINGS A camouflet device according to a preferred embodiment ofthe invention is illustrated in the accompanying drawings inwhichL. W a

FIG. 1 is a perspective view of a pipe line stake with which a camoufletdevice constructed in accordance with a preferred embodiment of theinvention, is particularly suitable for use;

FIG. 2 is a perspective view of a portion of the pipe line stake shownin FIG. 1 with a lower portion of the pipe line stake shown expanded bydetonation of the camouflet device;

FIG. 3 is a perspective view partially in section of the camoufletdevice according to the preferred embodiment of the invention;

FIG. 4 is a cross-sectional side view of the camouflet device shown inFIG. 3, with the parts of the device shown in the relative positionsthey initially occupy prior to use of the device;

FIG. 5 is a cross-sectional side view similar to that of FIG. 4 but withthe parts of the device shown in the positions they occupy duringinitial downward acceleration of the device into the ground,

FIG. 6 is a cross-sectional side view generally similar to that of FIG.5 but with the parts of the device shown in the positions that theyoccupy upon initial contact of the device with the ground duringcontinued downward acceleration of the device; and

FIG. 7 is a crosssectional side view generally corresponding to that ofFIG. 6 but with the parts of the device shown in the positions theyoccupy in a subsequent stage in which downward acceleration of thedevice has substantially ceased.

DETAILED DESCRIPTION Referring to FIG. 1 of the drawings, a pipe linestake assembly of the type with which a camouflet device according tothe present invention, is particularly suitable for use, is there shown.The pipe line stake assembly includes a fiat horizontal clamp 2 engagingand embracing the upper surface of a pipe line 4. Secured to the upperside of the clamp 2 is a vertical tube 6, having releasably boltedthereto a firing assembly 8.

The firing asembly comprises a guide tube 10, concentric andcommunicating with the tube 6, and having a closed upper end 12.Positioned within the guide tube 10 is a slender elongate pipe linestake 14 having an enlarged, piston-like upper end 16. A pointed lowerend of the pipe line stake 14 is slidably and snugly received within adeformable crush tube 18 extending concentrically and verticallydownwardly.

A propelling charge positioned within the guide tube 10, between theclosed upper end 12 thereof and the piston 16 is exploded to drive theelongate stake 14 downwardly into the underlying sea bed. A reactionplate 21, carried by barrel 10 reacts with the adjoining water to offsetrecoil force acting on this barrel. As the pipe line stake 14 is forceddownwardly, the upper piston end 16 enters and expands the crush tube 18which decelerates the stake so that it does not pass downwardly throughand out of the clamp 2.

Finally, a second or camouflet charge 22 at the lower end of the stake14 is exploded (FIG. 2) to deform the lower line stake portions 14(a)radially outwardly into 4 the surrounding earth to secure the stakeagainst release from the earth.

Of particular interest in the context of the present invention, is thecamouflet device utilized to expand the lower end of the pipe line stakebelow the surface of the ground. Although this camouflet device isdescribed with reference to a pipe line stake arrangement of the typeoutlined above, it will be appreciated that it is not limited to thisparticular application and may in fact be utilized in many other formsof ground engaging tool.

Moreover, it is not necessary that the tool with which the camoufletdevice is utilized must be explosively propelled into the ground. Othermethods of providing a downward acceleration to the tool, to cause it toenter the ground, may be utilized. For example, such methods may includethe use of resilient spring-type or compressed fluids such' as steam orair.

Referring to FIG. 3, the lower end of the pipe line stake 14 may be seento include a camouflet device 24 constructed in accordance with thepreferred embodiment of the invention.

The camouflet device 24 includes a hollow' cylindrical outer housing 14(a) integral with and forming the lower end portion of the pipe linestake 14. Threadedly received within the lower end of the pipe linestake 14 is a pointed, generally conical nose body 26 formed in twoportions, namely, a forward nose body 26a and a main nose body 26b.

The main nose body 26b includes a solid, axially and outwardly extendingcircular boss 28. Boss 28 is externally threaded about its periphery toengage an internally, threaded portion at the lower end of the pipe linestake 14. Tool receiving openings 30 are provided in the periphery ofthe main body 26b to enable insertion of a suitable tool for tighteningup the main nose body in threaded engagement to the pipe line stake.

An upper, radial flat face 32 of the main nose body 26b is provided witha central, circular, downwardly extending recess 34. The recess 34 isdefined by a flat, circular radial face 36 which is parallel to, andspaced below, the face 32 and by a peripherally and axially extending,cylindrical edge Wall 38.

The function of the recess 34 is to receive the lower end of anexplosive container 40. This container 40 comprises an upwardlyextending circular metal tube. The upper end of the explosive container40 is sleeved over a circular wooden boss 42 which is integral with, andprojects downwardly from, a disc-like wooden retainer plate 44. Thewooden retainer plate is connected with the nose body by a plurality ofthreaded retainer rods 46 which are disposed in cage-like configurationabout, and spaced from, the explosive container 40.

One end of each container rod 46 is threadedly engaged with the mainnose body 26b, while the upper end of each retainer rod extends throughthe wooden retainer plate 44 and is provided with a nut 48 bearingagainst the retainer plate. The nuts 48 of the various retainer rods maybe tightened up to cause the retainer plate to bear down on theexplosive retainer so that it is located firmly against the nose body,with its lower end extending into and received in the recess 34.

Porous filler material 50 is provided about the exterior of theexplosive container 40. This material 50 extends between the upper face32 of the main nose body 26b and lower face of the wooden retainer 44.Additional filler material 52, in the form of a disc coextensive withthe retainer 44, is provided on the upper surface thereof.

A camouflet charge of explosive 54 is packed within the interior of theexplosive container 40, between the face 36 of the nose body and thelower face of the boss 42 of the retainer. The amount of explosive issufficient to cause the body portion 14(a) to be blasted outwardly intostrips, upon detonation of the explosive, with the strips being curledout in the configuration generally disclosed in FIG. 2.

Also provided within the main nose body 26b is an axially extendingarming chamber 56. The arming chamber 56' has its upper end 58 spacedbelow the surface 36 which defines the recess for the explosivecontainer at the upper side of the main body. The vertically spaced,radially extending wall surfaces 36 and 58 define an internal wall 60ofthe main nose body 26b. A central opening 62 in the internal wall 60snugly receives an explosion initiator housing 64.

The initiator housing 64 comprises a metal tube having an open lower endwhich extends into the arming chamber 56 adjacent the end wall 58. Thehousing 64 extends vertically almost the entire length of the explosivecontainer 40 and has a closed upper end spaced below the boss 42 and theretainer 44. A plurality of vertically spaced openings 66 in theinitiator housing 64 place the interior of the initiator housing incommunication with the remaining portions of the interior of theexplosive container which are packed with the explosive 54. A retainingcollar 68, pressed about the exterior of the initiator housing 64 inabutting contact with the surface 36, locates the initiator housing 64in fixed relation to the main nose body 26b and the explosive container40.

The initiator housing 64 receives a concentric, axially extending lengthof detonating cord 70. The length of detonating cord, which in thepreferred embodiment is of the type known commercially as primer cordhas its external surfaces spaced from the adjacent internal surfaces ofthe initiator housing 64 and is movable upwardly and inwardly within theinitiator housing through the open lower end thereof. In the preferredembodiment, the length of detonating cord 70 has a burning time ofapproximately two seconds to constitute a delay train, although it willbe appreciated that by suitable variation of dimensions, this burningtime can be adjusted as required.

At its lower end, the detonating cord 70 is connected to a commerciallyavailable detonating cap or initiator 72. The initiator 72, in turn, isconnected with the forward end of a conventional blank cartridge 74.Upon detonation of the cartridge 74 (in a manner to be described), theinitiator 72 causes the lower end of the detonating cord 70 to beignited. The burning continues along the detonating cord in aconventional manner until, at the conclusion of the previously mentionedperiod of burning, the ignition is transmitted to the openings at theupper end of the initiator housing 64 to cause explosion of thecamouflet charge within the container 40.

The cartridge 74, which is a conventional .22 calibre blank cartridge,and the initiator 72 are carried by an inertial member 76.

The inertial member 76 comprises a solid metal cylinder mounted for freesliding motion within and along the arming chamber 56. The member 76 isprovided with a cartridge receiving, lower central bore 78 into whichthe cartridge 74 is pushed, with the head of the cartridge remainingoutside the inertial member at the lower end thereof. The dimension ofthe bore 78 is such that there is sufficient friction or interferencefit, once the cartridge 74 has been inserted, to retain it in position.At the upper end of the cartridge receiving bore 78 is another bore 80extending vertically through to the upper side of the inertial member toreceive the initiator 72 and the lower end of the detonating cord 70.

At the lower end of the arming bore 46, there is provided a relativelyenlarged, internally threaded bore 82. Bore 82 is threadedly engaged bya correspondingly configured, externally threaded male boss 84 which ispositioned on the upper side of the forward nose body 26a. The boss 84includes an upper, fiat radial surface 86 which constitutes a shoulderat the lower end of the arming bore. The inertial member 76 rests onsurface 86 in a lower or safety position of this inertial member.

Tool receiving openings 88 are provided in the forward peripheralsurface of the forward body 26a to enable it 6 to be tightened inthreading engagement with the main body 2612.

Extending centrally and entirely through the forward nose body 26a, isan internal passage 90. The passage 90 includes a lower portion 90a openat its lower end and an upper portion 90b, extending upwardly from thelower portion 90a. At the junction of the portions 90a and 90b of theinternal passage, there is a radially extending shoulder 92.

Mounted in the enlarged or upper bore portion 90b of the passage 90 is afiring member 94.

Firing member 94 has a cylindrical, disc-like base 96 slidably andsnugly abutting the interior of the enlarged upper bore 9012. Initially,on assembly, the disc-like base 96 rests against the shoulder 92 inabutting contact therewith. Extending upwardly from the disc 96, andintegral therewith, is a central cylindrical body 98. Body 98 isconcentric with and spaced radially inwardly from the upper bore 9012.At its forward end, the central body 98 has an integral, forwardlyextending forward body 100 of relatively reduced diameter. On theforward radial end of the forward body 100, there is positioned apointed firing pin 102. Pin 102 is aligned axially with a detonating cap104 in the head of the previously mentioned cartridge 7 4.

With the disc 96 in the lower or safety position, abutting the shoulder92, the firing pin 102 is spaced below the shoulder 86 by a sufiicientdistance to insure that the detonating cap 74 is spaced out of contactwith the firing pin 102. As an additional safety precaution, a reducedannular insert 106 is threadedly engaged in the upper end of theenlarged bore 90]; so that if the cartridge 74 should accidentally fallout of the carrier 76, it would rest on the upper edge of the insert 106with the detonating cap 104 still being spaced above the firing pin 102to avoid accidental detonation.

To retain the firing device 94 in the lower or safety position againstaccidental displacement therefrom, a detent in the form of an annularring of frangible cement 110 is positioned in contact with the forwardsurface of the disc-like base 96. However, on impact of the stake withthe ground (as will be described in more detail) earth entering thelower bore portion 90a of the passage 90 forces the firing device 94upwardly with sufficient force to brake the cement detent 110 so thatthe firing device 94 may move upwardly in the forward nose body 26a.Upward motion of the firing device is eventually limited by contact ofthe central body 94 with the lower surface of the insert 106. At thistime, the firing device is positioned in a firing position at which thefiring pin 102 is spaced vertically above the shoulder 86 so that it maybe impinged upon by the detonator cap 104 of the cartridge 74.

OPERATION Operation of the device follows a sequence of stagesillustrated in FIGS. 4-7.

An initial step is to explode the propelling charge 20 (FIG. 1) topropel the stake 14 downwardly into the sea bed. The effects of theexplosion of the propelling charge 20 are isolated from the camoufletcharge 54 by the filler material 50 and 52 surrounding the camoufletcharge. Upon initial downward acceleration of the stake 14, inertiacauses the inertial member to lag relatively behind the motion of thestake with the result that the inertial member 76 occupies an upperposition (FIG. 5) within the arming chamber 56. In this upper portion,the lower surface of the arming member 76 is spaced an appreciabledistance above the surface of the shoulder 86. At this time, the firingdevice 94 still occupies its lower safety position in which the firingpin 102 is spaced out of possible contact with any part of thecartridge.

As the stake continues its downward and still accelerating movement, thelower end of the forward nose body 26a commences to enter the ground(FIG. 6). As this occurs, earth is forced upwardly into the lower boreportion 90a of the passage 90. This earth acts like a piston upon thelower surface of the base 96 of the firing device, with suificient,upwardly directed force to shear the cement detent 110.

Continued downward motion of the pipe line stake causes earth to bedriven upwardly through the passage 90 until the firing device 94- hasbeen moved upwardly to its firing position, with the firing pin 102projecting above the shoulder 86. At this time, however, as downwardacceleration is continuing, the interial member 76 is still spacedsufficiently above the shoulder 86 to hold the cartridge 74 out ofcontact with the firing pin 102.

Downward motion of the pipe line stake continues, subject to thedecelerating forces provided by earth resistance and by the action ofthe previously mentioned crush tube 18 (FIG. 1). Eventually, the rate ofdeceleration, plus the effect of gravity, exceeds the previousacceleration. At this time, the inertial member 76 commences to falldownwardly within the arming bore 56. This downward motion carries thedetonating cap 104 of the cartridge onto the now exposed firing pin 102with sufficient force for the cartridge 74 to be detonated. Detonationof the cartridge 74 causes the initiator 72 to ignite the detonatingcord 70. This cord 70 continues to burn for the predetermined delayperiod which is sufficient for any remaining downward motion of the pipeline stake to be stopped by the decelerating forces previouslydescribed. Thus, at the conclusion of the predetermined period, the pipeline stake has come to rest. Thereupon, the explosive camouflet charge54 explodes to splay the adjacent portions of the pipe line stake 14outwardly, thus insuring that the stake is properly secured at its lowerend to the earth.

SUMMARY OF ADVANTAGES It will be appreciated that in providing acamouflet device according to the present invention, certain significantadvantages are provided.

In particular, the provision of a firing device which is held out of allpossible contact with the detonator prior to entry of the stake into theground, offers important advantages. For example, this constructioninsures that the camouflet charge will not fire prematurely before thelower end of the stake has reached its desired belowground penetrationlevel. In addition, the possibility that accidents might occur due toinadvertent dropping of the pipe line stake by personnel prior to use ofthe stake is also minimized.

The construction whereby the firing device is moved from the safety tothe firing position is also of particular significance. By utlizing asimple earth passage, earth is directly forced into the body and isutilized to arm the firing device. This construction is particularlysimple and low in cost. In addition, this arrangement is not subject tobreakage or damage problems when the pipe line stake is being utilizedon unusually hard packed earth.

In describing the invention, reference has been made to a preferredembodiment. However, those familiar with this disclosure and skilled inthe pipe line staking art may envision additions, deletions,substitutions, or other modifications which would fall within thepurview of the invention.

I claim:

1. A camouflet device adapted to have applied thereto an initialaccelerating force for propelling the device downwardly into the ground,the camouflet device comprising:

a longitudinally extending body adapted to be generally verticallydisposed during downward motion,

an inertial member mounted for free motion within said body, saidinertial member occupying a lower position thereof within said bodyunder the influence of gravity alone, said inertial member duringdownward acceleration of said body into the ground lagging behind themotion of said body to occupy an upper position therein spaced abovesaid lower posiition, a detonator connected with and carried by saidinertial member, detonating means mounted in said body for detonatingsaid detonator upon impact therewith, said detonating means in a firingposition thereof within said body positioned to be struck by saiddetonator when said inertial member moves to the lower position thereof,said detonating means in a safety postion thereof within said body beingspaced out of contact with said detonator in all positions thereof,restraining means, fixed with respect to said body, for

preventing movement of said inertial member towards said detonatingmeans beyond said lower position of said inertial member, yieldableretaining means, normally fixed with respect to said body, for normallyand positively maintaining said detonating means in said safety positionwithin said body and spaced out of contact with said detonator in allpositions thereof; and, passage means in said body providingcommunication between said detonating means and the lower end of saidlongitudinally extending body adapted to be generally verticallydisposed during downward motion, said passage means upon impact with theground causing earth to enter said body to contact said detonating meansto move said detoning means, with respect to said body, to said firingposition thereof against the restraining force provided by saidyieldable retaining means. 2. A camouflet device as defined in claim 1further including:

an explosive charge positioned within said body, said explosive chargebeing exploded by said detonator upon detonation thereof to causeoutward deformation of adjacent portions of said body. 3. A camoufletdevice as defined in claim 1 wherein said yieldable retaining meanscomprises:

shearable retaining means for initially retaining said body and saiddetonating means in fixed relation in said safety position, saiddetonating means being contacted with sufiicient force by the earthentering said passage means to shear said retaining means, saiddetonating means thereafter being moved by the earth entering saidpassage means to said firing position. 4. a camouflet device as definedin claim 2 further including:

time delay means interposed between said detonator and said explosivecharge for delaying explosion of such charge until a predetermined delayperiod after detonation of said detonator.

References Cited UNITED STATES PATENTS 3,222,842 12/1965 Luedloff et a152155 X 3,233,415 2/1966 Thomas 52-155 FOREIGN PATENTS 352,215 7/1931Great Britain.

ALFRED C. PERHAM, Primary Examiner US. 01. X.R.

